Ford Crown Victoria/Mercury Grand Marquis General Maintenance

I have a 2000 Grand Marquise with 50.234 miles. I see the 2005 and 2006 Grand Marquise call for 5w-20 motor oil. It&#146;s the same motor as in my 2000 question is can I use 5w-20 in my 2000 Grand Marquise. I currently use mobile full synthetic 5-30.

tritium: my 04 Crown Vic 4.6L calls for 5W-20, but I use Castrol Synthetic 5W-30, same as I use in my 04 Ram Hemi...I fail to use how a 30 weight when hot can hurt the engine in place of the reco 20 weight...besides, is the actual difference even noticeable from 20 to 30 weight???...maybe in the cold tundra of Alaska/North Dakota and Montana, but in Georgia winters, where the temp spends two weeks below freezing and we call that "cold?"

More air increases a tire's rolling diameter, hence the amount of travel per tire revolution. This enhances gas mileage.

That would mean that you could put on larger tires and get better mpg?? I believe the reason for better mpg with increasing tire pressure is that it reduces friction. Just like if you were driving with tires more narrow. Just don't keep the pressure that high if it's snowing, because then you'll want more traction.

"That would mean that you could put on larger tires and get better mpg?? I believe the reason for better mpg with increasing tire pressure is that it reduces friction. Just like if you were driving with tires more narrow. Just don't keep the pressure that high if it's snowing, because then you'll want more traction."

Excellent analysis. I wish I'd thought of that!

First, though, re your tire diameter remark:

Yes, of course larger tires will result in better gas mileage because, once again, rolling diameter is increased. This is equivalent to changing to a higher rear-end ratio. Done within the transmission this is called "overdrive". All three approaches yield more forward travel of the vehicle per engine revolution.

But your idea is cooler, more subtle, and I agree with it.

One can ask, for a fixed final drive ratio, including tire diameter:

With which tires will I get better mileage, those absorbing energy through added flex or those flexing less and running "harder"? I agree with you that absorbtion of energy by the softer tires, even when rolling diameters are meticulously held constant, will result in a larger throttle opening at the same vehicle velocity. It's because that lost energy, quite literally, has to come from somewhere. It WILL come from the engine and reduce mileage, just as you pointed out.

So it isn't just the rolling diameter which contributes to better mileage, but the reduction in rolling resistance as well, when the tires are run at greater pressure.

I guess I'm still slightly confused on the larger diameter creating better gas mileage. You said it's the same as having a higher gear in the transmission, but if you had an automatic transmission for example, putting larger tires on the car would require more power from the engine to make one rotation of the tire, so the car would remain in a lower gear longer to provide. So I still don't see what would be gained in mpg by just adding a larger tire size. To me it seems like increasing tire size would would require more gas to be used to maintain the same speed.

Here's a quote:http://autos.msn.com/Advice/Article.aspx?contentid=4018909"Even larger tires can have an effect. A tire with a larger "footprint" on the road that doesn't have a special rubber compound designed to improve fuel economy has more rolling resistance than a comparable smaller tire, and this can lower fuel economy"

There's always a trade-off between fuel economy and performance when it comes to tires. That "larger footprint" of a more agressive tire kills your fuel economy, but the same frictional forces that do that are what allow you to corner better.

A larger tire diameter effectively translates the rotation of the hub to a higher velocity at the outside. Just look at a record or CD as it's turning: the hub is fairly slow, but the circumference is moving very quickly. v = r*w, where "v" is the linear velocity (tangential to the circumference), "r" is the radius of the circle, and "w" is the angular velocity. Thus, the bigger the radius, the larger the linear velocity, which translates into a faster-moving car. Or, you could look at it from the other way: the less fast the hub has to turn in order to maintain a given speed, and thus the less fast the engine has to turn, thereby saving fuel.

I guess I'll stop because my comments are becoming "circular" but when you say, "the less fast the hub has to turn in order to maintain a given speed, and thus the less fast the engine has to turn, thereby saving fuel." but the transmission is in between the tires and engine, so you'll still need more power in the engine to maintain the higher speed, regardless of whether or not the higher speed

Using your CD example, if you put your hand on the edge of the CD when it's spinning (like the tires on the road), it's easy to stop the CD from moving, as compared to touching the inner wheel moving. So for a given CD motor, you can stop it easier on the edge then close to the center. To make it so when you pressed against the edge of the CD, the CD kept moving, you'd need a more powerful motor, which is the same as needing more power coming from an engine, which needs more gas to get that power.

You can stop a CD by the edge better than in the middle because the torque you're applying is larger: torque is the product of the force times the radius, so the further out you grab, the higher the torque you apply (that's why torque wrenches have such long handles).

However, in the case of a car, remember that it takes almost no power to keep a car moving - maybe only 15 hp or so to maintain a given highway speed. This is how the whole V8-6-4, "Multi Displacement System", etc. are able to be so effective at saving fuel. For us Panther folks who run on all 8, all the time, there are gobs of excess power that our motors make at highway speed that is virtually useless; thus, even though it may take more energy to get the outer radius of large tires spinning against the friction of the road, the engine doesn't need to spin any higher to transfer its already-excess power to the wheels. I think that that makes sense, anyway . My background is electrical engineering, so it's been a while since I've used any mechanical stuff!

Any other G/M or C/V owners using the Back engineered 5w-20? I have read on other forums where it causes premature engine wear. And Ford is only using it to meet the CAFÉ standard. I started using it 2 months ago in my 2000 G/M no problems yet.

I have a 1994 Mercury Grand Marquis with about 119,000 miles on the odometer. I discovered about a week ago when I checked my oil level because the oil light came on that my oil level was quite low. It took three quarts to bring it up to the full line on the dipstick. Yesterday I added about three more quarts.

Not being a mechanic myself, I always thought that if a car was using oil, you would see it and smell it. Not so in this case. What could be wrong to cause the car to start using that much oil with no symptoms? How serious/expensive could it be?

The most obvious sign of a car using oil is a puff of white smoke when a car is first started after sitting shut off for a while. In this case, worn valve seals permit seepage of oil into the cylinders.

The CV and GM recommend a transmission service at 30,000 miles. I have read all the pros and cons of the usual drain or the power flush. What do most of you do? i think it is important to drop the pan and some say the flush can cause problems.

In 90k miles the tranny oil has been changed twice. When it starts to shudder again, it'll be changed again. The first change used Mercon V Synthetic. The last change used non synthetic, a lot more economical, and can't tell the difference. This is regarding our 95 T Bird with 4.6 and AOD tranny.

The 94 Town Car has 127,000 miles and is still going on it's 2nd change.

Just be sure to drain the torque converter too. Drop the pan? Wouldn't hurt if high mileage.

While I honestly did not see any improvement in tranny performance, I do not expect to, any more than chganging engine oil shows noticeable improvement...I just do it for routine maintenance, hoping that the tranny will shower me with $150K miles of service or more...

I've heard from a few mechanics that tranny fluid should never have to be changed for the life of a car. My '85 Grand Marquis was, and '80 Trans Am is, running original tranny fluid with no signs of performance degradation. It may be a different story for new cars, though; more compact designs with more electronics may require more frequent changes, but every 30,000 miles seems kind of crazy to me. I guess it's just the automaker covering his rear (speaking of which, a rear end fluid change strikes me as unnecessary in most cases, too!).

I can appreciate your view, but I just cannot see leaving any fluid in there that long...to me, tranny fluid gets as abused as engine oil, but we go longer because it is 18 quarts as opposed to 5-7...but, hey, thats just me...

was the color of the fluid the same as your coolant???... if yes, could there be a water pump leak that drains along the block and falls somewhere that does not directly correspond to an area of leaking???...kinda like the roof that leaks at the left end, but the water drips and falls on the right end, the true leak is nowhere where you find the evidence of the leak...